1. Field of the Invention
This invention pertains, in general, to the field of refrigeration and air conditioning, and more particularly, to an integrated, ambient-energy-assisted system for water and space heating and cooling purposes.
2. Summary of the Prior Art
Many heating and cooling systems have been designed in recent years which rely partly or wholly on solar radiation for their energy input. Such systems may be divided into two general categories:
One wherein a fluid is circulated through a solar collector or receiver where it absorbs heat which is then transferred by means of a heat exchanger to another fluid, e.g., water for domestic use, or to a thermal storage medium such as low temperature melting salts, etc.
The second general category of heating systems use a low temperature boiling point working fluid or refrigerant which undergoes a thermodynamic cycle, including evaporation in the solar panel, superheating by compression, and condensation in a heat exchanger. An example of the latter type is shown in U.S. Pat. No. 4,392,359 to Franklin. A still further example of the second type of system is shown by Charters, et al., in U.S. Pat. No. 4,302,942.
Many variations on the above two types of systems are known, including hybrid systems which combine the aforementioned two general approaches, such as that disclosed by Ecker in U.S. Pat. No. 4,308,042. The known systems further differ in the working fluids and refrigerants used, among other points of differentiation.
Existing heat pump systems can provide both heating and cooling by use of a so-called "reversing valve" to reverse the flow of refrigerant through the system, and thereby switch from a heating mode to a cooling mode. For example, in the heating mode, a solar collector panel operates as the evaporator in which is heated a refrigerant fluid, while the heat exchanger coil works as the condenser where the hot refrigerant heats air or water. By reversing the flow of refrigerant, the air heating coil can be made to operate as the evaporator, absorbing heat from the interior air in an enclosure. The heat is dissipated through the exterior solar panel to the outer atmosphere, the panel now operating as the condenser.
A major shortcoming of such prior art systems has been the inability to provide simultaneous heating and cooling. A typical residential site has a steady requirement for hot water in addition to either heating or cooling of the interior air space. The requirement of heat input to a water heating system simultaneously with a cooling requirement of the interior space could not be met by any of the known, relatively-simple heating/cooling systems. Even disregarding the inability to meet simultaneous heating and cooling requirements, conventional heat pump systems relying on reversing valves to alternate operating modes often suffered from reliability problems and shortened component lifetimes due to the additional stress imposed on the components by the flow reversals and consequent reversing pressure differentials imposed on the various system components. Still further, the use of reversing valves adds to the complexity and cost of the system.